# `Storehouse.Renderer.Imgproxy`
[🔗](https://github.com/hattoriai/storehouse/blob/v0.2.0/lib/storehouse/renderer/imgproxy.ex#L1)

The URLs of variants [imgproxy](https://imgproxy.net) renders
(`Storehouse.Renderer`): signed, so only the presets' sizes are ever
rendered, and the same every time, for a CDN in front of it to keep.
The app renders nothing, and stores nothing.

    config :storehouse, Storehouse.Variants,
      renderer:
        {Storehouse.Renderer.Imgproxy,
         url: "https://images.example.com",
         key: System.fetch_env!("IMGPROXY_KEY"),
         salt: System.fetch_env!("IMGPROXY_SALT"),
         source: "s3://my-bucket/"},
      presets: [photo: [widths: [640, 1280, 1920], format: [:webp, :original]]]

A preset is written as imgproxy's processing options:

  * a width alone is `w:<width>`; a box, `rs:fit:<width>:<height>`, or
    `rs:fill:<width>:<height>` with `fit: :cover` and its gravity
    (`g:ce`, `g:sm` for `:attention` and `:entropy`, `g:fp:<x>:<y>`);
  * `q:<quality>`, when the preset gives one;
  * `f:<format>` for one format; none for `:original`, or for several,
    which imgproxy chooses itself by `Accept` (with
    `IMGPROXY_AUTO_WEBP` or `IMGPROXY_AUTO_AVIF` on);
  * `scp:0` for `profile: :keep`, `sm:0` for `metadata: :all` (imgproxy
    strips metadata by default), a background as `bg:<hex>`;
  * then the preset's `options: [imgproxy: "…"]`, as they are:
    `"sh:0.3/fq:webp:86:jpeg:90"`.

imgproxy never enlarges an image unless it is told to.

## Options

  * `:url` - imgproxy's address (or the CDN's in front of it). Required.
  * `:key` and `:salt` - imgproxy's, in hex (`IMGPROXY_KEY`,
    `IMGPROXY_SALT`). Without them, URLs are unsigned (`/insecure/`):
    for development only, as anyone could ask for any size.
  * `:source` - where imgproxy reads the original: a prefix the key is
    put after (`"s3://my-bucket/"`, `"local:///"`), or a function of the
    file that gives its address. The default is the store's URL of the
    file (`Storehouse.url/2`).
  * `:extension` - `true` ends the URL with the format's extension
    (`…/<source>.webp`) in place of `f:`. The default is `false`.

## Its own addresses

For URLs of another shape (a CDN's Worker that signs them itself),
`signed_path/2` gives the path imgproxy is asked, and a renderer of the
app's own builds the rest.

# `path`

```elixir
@spec path(Storehouse.Variant.t(), Storehouse.File.t(), keyword()) :: String.t()
```

The path of `variant` for imgproxy, not yet signed:
`/<processing options>/<encoded source>`.

# `signed_path`

```elixir
@spec signed_path(String.t(), keyword()) :: String.t()
```

`path` signed with the options' `:key` and `:salt`: `"/<signature><path>"`,
as imgproxy checks it (HMAC-SHA256 of the salt and the path), or
`"/insecure<path>"` without them.

---

*Consult [api-reference.md](api-reference.md) for complete listing*